National Geographic : 1989 May
NATIONAL GEOGAA I MAGAZINE GlO]tlPHIA NGS PHOTOGRAPHERVICTORR. BOSWELL,JR. Slowly Restoring Leonardo's Masterpiece M illimeter by millimeter the restoration of Leonardo da Vinci's "Last Supper" (GEO GRAPHIC, November 1983) continues. Work has been completed on about half the mural, located in the refectory of a former monastery in Milan, Italy. Dr. Pinin Brambilla Barcilon, who has executed the restoration since 1977, is now working on the face of Christ and the upper part of the table. Dr. Pietro C. Marani, inspector for the superintendent of fine arts in Mi lan, says another two years are needed to finish repairing damage from expo sure to sunlight and fluctuating tem peratures, stripping the layers of paint added by earlier restorations, and removing the grime accumulated over centuries. Meanwhile, Marani hopes to install an air-conditioning system in the monastery this year to help prevent renewed deterioration as restoration work is completed. To reduce humid ity, which also can cause serious dam age, the number of visitors allowed to see the "Last Supper" has been limited to 25 at any one time. Uncovering the Past: the Mastery of Fire When did our ancestors first learn to use fire? That prehistoric advance -which ranks in impor tance with stone-tool making-seems to have occurred much earlier than scientists had thought. The most recent evidence comes from Swartkrans, a large cave excava tion near Pretoria, South Africa. Ar chaeologist C. K. Brain found charred animal bones scattered through lime stone strata about a million years old and older. Experiments show that the bones were heated at temperatures as high as those occurring in campfires. And in the cave layers, remains of the ape-man Australopithecusrobustus and a larger brained hominid, Homo erectus (GEOGRAPHIC, November 1985), suggest who tended those fires. Previously the earliest strong evi dence of fire use came from Zhoukou dian, a cave near Beijing, China. There, amid remains of Homo erectus, a layer of ash and burned animal bones dates from about half a million years ago. Black-footed Ferret Population on the Rise Things are looking up again for the black-footed ferret, which has gone through a perils-of-Pauline existence over the last decade. The little animal, a member of the weasel family, had been considered extinct until a small group was found amid prairie dog colonies near Mee teetse, Wyoming, in 1981 (GEO GRAPHIC, June 1983). Their known population reached a peak of 129 in 1984 before a combination of a plague that killed prairie dogs, their chief prey, and canine distemper, which kills ferrets, caused it to crash. Authorities then captured ferrets from the wild and started a breeding program. Early in 1989 the ferret population was up to 58, according to Tom Thorne, a veterinarian with the Wyo ming Game and Fish Department, who is in charge of the program. Fifteen fer rets have been sent to two other facili ties to prevent any new outbreak of illness from killing all captive ferrets, as happened in 1985. Thorne plans to reintroduce some ferrets into the wild when the population reaches 500, which he hopes will happen by 1991. Soviet Geography Poll: Pandas in Panama? A international survey conducted last year by the Gallup Organiza tion for the National Geograph ic Society showed that Americans have a woefully limited knowledge of geog raphy. As Society President Gilbert M. Grosvenor reported (GEOGRAPHIC, November 1988), young Americans did especially poorly when compared with residents of eight other nations, finishing last in a test of general geo graphic knowledge. A few of them said they thought pandas came from Pana ma and kangaroos from Lebanon. Now Americans will be able to see how they compare with people in the Soviet Union when it comes to geo graphic expertise. Gallup will join with the Institute for Sociology of the U.S .S.R. Academy of Sciences in a Society-commissioned poll of 1,500 Soviet citizens, a thousand of them outside the Moscow area and the re mainder in the capital. The Soviet respondents will be asked virtually the same questions as those posed in the earlier survey-questions to find out what importance they place on geo graphy and to test their map-reading skills by requiring them to locate specific places or bodies of water. Clovis Cache Discovery Points Up Old Debate The discovery of a major cache of Clovis points in central Washing ton (GEOGRAPHIC, October 1988) has helped refocus attention on the vexing question of when the Americas were first peopled. Such distinctively fluted spear points, dating from 11,500 to 10,500 years ago, have been found in southern Canada and much of the United States. Clovis points have turned up also at a number of sites in Mexico, Guatemala, and Costa Rica (map, below). Most were found on the surface and cannot be dated. But Alan Bryan of the University of Alberta, who excavated a Clovis A point in Guatemala, was able to date that site at about 10,700 years ago. A site in southern Mexico yielded a Clovis-like point dating back to 9,400 years ago. Archaeologists agree that the West ern Hemisphere was populated by people who crossed a land bridge from Asia into Alaska. By about 12,000 years ago they had begun to spread southward through the Americas via an ice-free corridor east of the Rocky Mountains, most believe, using sharp Clovis spearpoints to kill large game. But Bryan, noting findings of non Clovis artifacts 13,000 and more years old in South America, thinks that the original dispersal of people, perhaps along the Pacific coast, was much earlier and that Clovis points were just one of several technologies developed by their descendants.